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Abstract: This study has analysed for the first time fish composition and assemblage structures of three small macrotidal estuaries of the Eastern English Channel (EEC) and has explored the influences of 19 biotic and abiotic variables on the fish assemblages. Fish from Canche, Authie and Somme estuaries were collected during spring (June 2006 and May 2007) and autumn (September 2006) along the estuarine gradients using a 1.5m beam trawl. Using identical sampling protocols, the study also analysed and compared for the first time taxonomic and functional aspects of the fish assemblages in 15 estuaries located along the Atlantic and English Channel coasts. SIMPER analysis showed high similarities in fish assemblages in the three EEC estuaries and during either spring or autumn periods. However, intra-estuary similarities were relatively low, indicating that fish assemblage structures (species richnesses or abundances) were more variable within the estuary (salinity gradient) than between estuaries and/or seasons (spring vs autumn). Although numerous environmental variables were included in the study, only 47% of the variability observed in the fish distribution was explained. Fish spatial variations in the EEC estuaries are mostly driven by abiotic variables as opposed to biological interactions. As indicated by CCA, salinity and muddy sediments were the two most important factors structuring the fish assemblages. The macrobenthos being very abundant in the EEC estuaries (580–1121ind. m−2), the availability of potential prey is probably not a limiting factor in the utilization of estuaries by fish. Contrary to the majority of French estuaries dominated by estuarine species (ES), the fish assemblages of the EEC estuaries are clearly dominated by marine migrant (MM) species (65% on average) with high abundance of juveniles (mostly young-of-the-year). Cluster and SIMPROF''s analyses distinguished the functional structure of the 15 estuarine fish assemblages into different clusters. The three EEC estuaries form a similar group with the largest French estuaries (Seine, Loire and Gironde). The latters were characterized by higher MM/ES ratio compared to the other French estuaries. Freshwater flow and tidal range were the main factors associated with this group of estuaries. The results of the present study do not indicate that anthropogenic impacts (chemical contamination) on estuaries affect their ecological functioning as described by the fish ecological guilds. It is suggested that the guild approach may not be useful to provide valuable information on the ecological status of estuaries. [Copyright &y& Elsevier]

Cysts of metacercariae were obtained on 2 dates from juvenile sole Solea solea sea-sampled in an area of mussel cultivation (Pertuis Charentais, Bay of Biscay, France). An initial assessment of parasite genus and infestation level was based on 192 cysts extracted from 2 fish samples, taken in August (n = 20) and December 2000 (n = 14). Our results confirmed the sole as second intermediate host of bucephalid trematodes of the genus Prosorhynchus, which has not previously been noticed in Atlantic stocks. Prevalence, ca. 65% on both dates, indicated an substantial infestation of these small fish, with a mean abundance of parasites increasing from August (3.3 +/- 1.1) to December (8.1 +/- 3.4). Cysts were localised in all body parts of the host, and positioning varied depending on sampling date. However, the cephalic area was always the most infested (72.7 and 49.1% in August and December, respectively). Parasite measurements suggested a protracted infestation process, which may be initiated in spring during sole settlement. Most of the largest metacercariae had the rhynchus characteristics of P. crucibulum, though the possibility of them being other species (P. squamatus, P. aculeatus) could not be excluded. As Mytilus edulis is the first intermediate host of Prosorhynchus spp., possible relationships between mussel culture and sole parasitosis are discussed.